The Biorheology-Biophysics Core is based on the central hypothesis that: Flow behavior of sickle blood in vivo depends on unique biorheological and biophysical characteristics which can only be evaluated by a battery of tests specific for these characteristics. The specific aims of the Biorheology-Biophysics Core Include: 1) Dr. D. Kohn's Project is to provide relevant red blood cell microrheologic and morphologic data, and to supply associated biophysical information as an aid in assessing the properties of cells produced by this project: 2) Dr. V.Kalra's project is to provide relevant blood-RBC rheological and biophysical data, and to provide defined flow systems for quantitative of RBC or WBC interaction with endothelial; 3) Dr. H. Meiselman's project is to provide relevant RBC rheological, morphological and biophysical measurements, and to provide supporting rheological and biophysical systems and techniques; 4) Dr. T. Coates's project is to provide relevant WBC rheological and biophysical data, and to provide data for cell-cell interactions in defined flow systems; 5) For all investigators associated with the USC Comprehensive Sickle Cell Center, to provide general biorheological and biophysical consultation. It should be noted that successful completion of the above mentioned aims should provide new information regard the rheological and biophysical properties of sickle blood and insight into the use of these data as supportive information for improved patient care. It is thus anticipated that the information resulting from studies by this Core will increase the understanding of the circulatory events which occur in sickle cell diseases.